Machine tool



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ATTORNEYS 8 Sheets-Sheet 3 R. D. BENNETT MACHINE TOOL June l, 1948.

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R. D. BENNETT MACHINE TOOL 8 Sheets-Sheet 4 Filed Aug. 16, 1943Pnt-:5035 Ex/Mwr June l, 1948. R. D.BENNr- 'TT 2,442,635

MACHINE Tool.

Filed Aug. 16, 1943 8 Sheets-Sheet 5 LEFT mnr INVENTOR 691cv 55AM/Err BY.d M, 9W, www 4 M ATTORNEYS June 1, 1948. R. D. BENNEl-r MACHINE Tool.l

8 Sheets-Sheet 6 Filed Aug. 16, 1943 June l, 1948.

MACHINE TOOL 8 SheetsPSheet '7 Filed Aug. 16, 1943 ATTORNEY June 1948.R, D; BENNETT 2,442,635

I MACHINE TOOL Filed Aug; 16, 1945 A '8 Sheets-Sheet 8 ATTORNEYSPatented June l, 1948 MACHINE TOOL Racy D. Bennett, Detroit, Mich.,assigner to Vinco Corporation, Detroit, Mich., a corporation of MichiganApplication August 16, 1948, Serial No. 498,763

l Claims. l

This invention relates to precision tools, such as spline and geargrinders.

The object of the invention is to provide a fully automatic machinewhich will effect the final shaping of gear teeth, splines and the like,with extreme accuracy and at the same time at a production rateheretofore possible only for work having much greater manufacturingtolerances.

One of the greatest difficulties in producing machine elements such asgears, splined shafts and the like to accurate dimensions, that is,within tolerances of, say, plus or minus one tenthousandth of an inch,is inaccurate indexing. In the ordinary indexing head a notched indexwheel with the notches accurately spaced to the exact positions for thedesired sequence of operations is attached to the work-supportingspindle and at each partial rotation of the spindle a tooth-supportingmember carried by the indexing head is Withdrawn from the notch and thework turned through the necessary angle for the tooth to engage the nextsucceeding notch. Exact accuracy in positioning the notches in the indexwheel will not, however, insure accurate indexing unless such factors aslost motion, momentum of moving parts, vibration, and other similarfactors, are taken care of, and one of the objects of my invention is toprovide an improved indexing mechanism which eliminates or so reducessuch factors that the quantity production of gears and splines withtolerances of less than one ten-thousandth may be successfully carriedout.

A further object of the invention is to provide an improved means forcontrolling the movement of the work-carrying table with respect to thegrinding wheel or other tool whereby the speed of movement of the table,its acceleration and deceleration, as well as its amplitude of movementmay be accurately and automatically controlled through a wide range.

A further object of the invention is to provide an automatic cyclecontrol for a machine tool of this character whereby the movements ofthe table and-indexing head may be variously modied to produce differentcycles of operations which are automatically repeated any desired numberof times.

A further object of the invention is to provide an automatic machine ofthe character described Wherein failure of any of the operating parts ofthe machine will cause an instant stoppage of the machine without damageto the grinding wheel or other tool or the work.

A further object of the invention is to provide an improved indexinghead which not only gives accurate indexing, but may also be givenpredetermined additional movements i'or certain special operations aswill be later described.

In the accompanying drawings I have illustrated a preferred embodimentof my invention, the particular machine illustrated being an automaticspline grinder for grinding the splines of aircraft engines to receivethe propellers. The tolerance permitted in grinding splines of thischaracter is plus or minus two ten thousandths of an inch. The machineillustrated will automatically grind splines within these limits at`much greater speeds than heretofore obtainable within tolerances of thisorder. Referring to the drawings:

Figure 1 is a side elevation of my improved Fis. 7 is a side elevationof the indexing headwith the adjacent cover removed;-

Flgs. 8 and 9 are sectional views of the hydraulic motor employed fordriving the index head;

Fig. 10 is a detail view showing one of the safety switches;

Fig. 1 is a detail view on an enlarged scale showing a portion of themechanism for controlling the operation of the table;

Fig. 12 is a diagrammatic view showing the hydraulic circuit foroperating the indexing head and the -work-supporting table;

Fig. 13 is a diagrammatic view of the electric circuit whereby thevarious cycles of operations are automatically obtained;

Fig. 14 is a sectional view of a modified indexlng head whereby the workmay be turned backward and forward through limited distances withoutinterfering with accurate indexing; and

Fig. 15 is a detail view on line lli-i5 of Fig. 14.

In the drawings I have illustrated a spline grinder of the` type whereinthe grinding wheel is supported on a stationary column and the shaftwith the splines to be ground is carried by a longitudinallyreciprocating table which moves the shaft back and forth during thegrinding operation. Referring to Fig. l, the base of the machine isindicated at I which is preferably a hollow box-like structurecontaining the electric motor 2, the oil sump 3 and the pumps 4 and 5,which supply the operating fluid under pressure for shifting thereciprocating table 1 and operating the hydraulic motor through whichthe indexing head is rotated. The pump 5 is connected through a suitablecontrol valve system, shown in greater detail in Fig. 12, to a cylinder6 whose piston is connected to the reciprocating table 1 on which theindexing head 8 and tail stock 9 are supported. It will be understoodthat the indexing head and tail stock are mounted on the reciprocatingtable for longitudinal adjustment in the usual manner. The column Iwhich carries the grinder I'I is also mounted for adjustment on a trackextending along one side of the frame I. The table 1 is provided withadjustable stops 82, see Fig. l1, which engage and operate at eachmovement a trip rod 94 mounted for limited movement on the flxed frameof the machine. The position of the stops 82 determines the extent oftravel' of the table, and the movement of the rod 94 trips a controlswitch which initiates the next operation In the cycle for which thecontrol mechanism is set.

In the operation of the machine the shaft on which the splines are to beground is supported between the centering pins of the indexing head andthe tail stock and the table is set in motion to reciprocate the shaftlongitudinally beneath the grinding wheel, with the periphery of thegrinding wheel engaging the spline on the upper side of the shaft. Ateach back-and-forth movement of the table or at any other desiredinterval, the indexing head is rotated a partial revolution to bring thenext spline on the circumference of the shaft into alignment with thegrinding wheel. The locking mechanism of the indexing head maintains theshaft accurately in p0- sition during the reciprocation of the table andwhen the table is at rest the indexing head is operated to give the workanother partial rotation and thus bring the next succeeding spline intoline with the grinding wheel. This operation is repeated until all thesplines are ground to a proper depth and shape.

I will rst describe my improved indexing head.

lThe centering pin of the indexing head is carried by a shaft I2 mountedin ball bearings I3 carried ina journal I4 cast integrally with thecasing of the indexing head (see Fig. 4)..- The shaft I2 projects to therear beyond this bearing and is provided with a rigidly attached hub I5to which the indexing wheel I8 is xedly attached by any suitable means.Also attached to the hub I5 is a gear I1 through which the shaft I2 ofthe indexing wheel is rotated by means of a small fluid motor I3supported on the adjacent wall of the casing as illustrated in Fig. 2,and with its driving pinion in mesh with the gear I1. Any suitable typeof hydraulic motor may be employed, but I preferably employ a motor ofthe radial cylinder reciprocating piston type such, for example. asshown in Figs, 8 and 9. Liquid under constant pressure is delivered tothe fluid motor by the pump 4 andreturned to the sump through iiexiblehose connections as illustrated in Fig. l.

The index wheel I6 (see Fig. 2) has a series of peripheral notches 22accurately spaced the desired distance apart and shaped to ilt a lockingtooth 23 on the end of a rocker arm 24 which is carried by a supportingplate 25 as shown more particularly in Figs. 3 and 4. As here shown theplate 25 is supported on a bearing attached to the face of the journalI4 between the hub I8 and the main bearing I3. The supporting plate 25is locked in adjusted position by a clamping bolt 2B mounted in the sidewall of the casing and working through an arcuate slot in the upperportion of the supporting plate.

For accurately positioning the supporting plate I preferably provide amicrometer adjustment consisting of two cams 21 pivotally mounted on thewall of the casing and positioned to engage on the opposite sides of thelaterally projecting arm 25a on the supporting plate 25. Adjustingscrews 28 are threaded through the wall of the casing with their roundedends engaging the opposite faces, respectively, of the cams 21.

The arm 24 is pressed against the periphery of the index wheel by aspring-pressed plunger 23 mounted on the plate 25, and when the notches22 in the periphery of the index wheel successively reach positions inregistry with the tooth 23, the indexing wheel will be stopped and heldagainst rotation until the arm 24 is rocked against the tension of thespring 29, For rocking the arm 24 I preferably provide a second rockingmember 30 one end of which bears on an adjusting screw 3| in the end ofthe rocking arm 24, The opposite end of the rocking arm 33 is providedwith a cam roller resting against the tapered end of an operating pin 32supported in the side wall of the casing and projecting at its oppositeend into a cylinder 33 supported on the outer face of the wall within ahousing 34 forming part of the casing. The cylinder 33 contains aplunger 35 which is spring-pressed toward the outer end of the cylinder,that is, in a direction to relieve the pressure on the operating pin 32.Fluid under pressure from the pressure line of the pump 4 leading to thehydraulic motor I3 is delivered to the cylinder 33 to operate theplunger 35 and pin 32 to thereby rock the arm 30 and lift the tooth 23out of its notch in the index wheel.

The now of uid to the cylinder 33 is controlled by the control valve 36which serves also to reduce the speed of the hydraulic motor I8 as theindex wheel nears the completion of its movement. 'Ihis valve is shownin Fig. 2 in position to admit fluid to the cylinder 33 but before thepiston 35 has commenced its movement, It comprises a cylindrical valvecasing and a piston valve 31 normally maintained in elevated position bya spring and pushed downward as shown by the solenoid 33 when its coilis energized. One port 38 of the valve casing is connected to thecylinder 33 by a pipe leading from port 38 and this port is cut off fromthe pressure port 40 when the valve is in elevated position by themiddle head 4I. In this position of the valve the port 38 is connectedto the exhaust port 42 which is connected by a pipe 43 with the fluidreturn passage leading to the fluid supply sump 3.

The pressure line to the motor I8 is continuously open so that the motormaintains a continuous driving torque on the index wheel, The returnline, however, is partially blocked 0E -by a plug 44 having a passage ofreduced diameter. Above the plug 44 the return line is connected to thevalve chamber by a port 43 positioned to be closed by the lower head 45of the valve 31 when the valve is in elevated position.

The valve 31 is operated to admit fluid under pressure to the cylinder33 by the solenoid 33 when its coil is energized after the reciprocatingtable 1 comes to rest at the end of its movement in one direction. Whenthe valve 31 is depressed by the solenoid the port 38 is connected tothe pressure side of the circuit of the hydraulic motor and the piston35 will shift the plunger 32 toward the right as shown in Fig. 2. Themovement oi' the plunger 32 rocks the arm 24 and lifts the tooth 23 outof the notch in the periphery of the indexing wheel, permitting thelatter to be rotated by the hydraulic motor I8, The circuit through thesolenoid coil is broken shortly before the succeeding notch of the indexwheel reaches the tooth 23 so that the spring within the cylinder 33will return the pin 32 to its outward position, releasing the nm 24which will be free to move under the action of the spring 29 when thenext notch in the indexing wheel comes into registry with the tooth 23.When the circuit through the solenoid 39 is broken the valve 31 will beelevated by its spring, thereby cutting ofi. the pressure from thecylinder 33 and connecting the port 38 to the exhaust port 42 so thatthe arm 24 will be released as described. The return oi' the valve toits upper position also reduces the speed of rotation of the indexingwheel, so that the impact of the notch with the tooth will be reduced toa negligible value and the indexing wheel will be brought to restwithout jam or shock.

When the valve body 31 is depressed by the solenoid its lower head 45uncovers the port 46, thereby providing an unrestricted ow of theexhaust fluid from the motor to the pipe 43 leading to the returnpassage, but when the valve is elevated by its spring as described theport 46 is cut oif and the exhaust fluid from the motor must passthrough the restricted passage in the plug 44. i

For de-'energizing the solenoid 39 as the index wheel nears thecompletion of its movement I provide a second rocker arm 50 mounted onthe same pivot as the rocker arm 24, rocker arm 50 being provided with atooth I which also rides on the periphery of the index wheel I6 inposition to engage the notches 22 in the index wheel. The tooth 5I isbeveled on its leading edge so as not to stop the rotation of the indexwheel but to be lifted out of the notch by the continued rotation of thewheel. The arm 58 is positioned to rest by gravity on the periphery ofthe index wheel and as the notch 22 passes under the tooth 6| the toothwill drop into the notch, thereby opening a. switch 52 (see Fig. 5) inthe circuit of a relay which controls the operation of the solenoid 39.As the rotation of the index wheel proceeds the rear edge of the notch22 will engage the beveled inner face of the tooth 5l, thereby rockingthe arm 50 and closing the switch 52. Closing the switch 52 does not,however, immediately reenergize the solenoid 39, because of theconstruction and operation of the relay as will be later described. Thecontinued movement of the index wheel brings the notch into registrywith the latch which drops into the notch, stopping the movement of thewheel, and closing a switch 41 which, as will be later described, startsthe table on its return movement.

By reducing the impact in the manner described, the 'indexing wheel maybe operated at a much higher rate of speed, reducing the period of dwellbetween the successive movements of the machine bed, and therebyspeeding up the operation of the machine without increasing the 6 speedof movement of the work with respect to the grinding wheel.

It is important that the pressure of the indexing wheel against thelocking tooth 23 be constant so that the compression of the metalsurfaces will be uniform. Otherwise, however exactly the index wheel ismade, there will be a variation in the movement from one notch toanother, depending upon the degree ofV pressure maintained between theparts at dli'erent times in the cycle of operations, I find that a.hydraulic motor of the type disclosed, when operated by oil underconstant pressure, will maintain a constant torque on the driving shaftof the motor and consequently a constant pressure between the indexwheel and the locking arm.

This motor is illustrated in Figs. 8 and 9 and comprises a stationaryblock having four cylinders 60'bored radially in the block andcommunicating With a central crank chamber 6|. The pistons 62 areconnected to a common crank pin 63 which projects from the end of acrank shaft 64. The crank shaft is supported for rotation in asupporting block 65 which is bolted against the adjacent wall of thecasing of'the indexing head, as shown in Fig. 2. A rotary valve 66 isattached to the shaft 64 between the bearings and is provided withannular pressure and exhaust ports 61, 68, respectively, which in turncommunicate with the pressure and exhaust passages 69 and 10communicating with the pump 4.

Passages 1|, formed by bores in the supporting block 65, communicatewith the outer ends of the cylinders and successively connect thecylinders with the pressure and exhaust passages 69 and 10. The passages69 and 10 register, when the motor is attached to the casing wall, withpassages extending through the wall and registering in turn withpassages formed in a base block 12 bolted against the outer face of thewall of the casing and furnishing a support, as shown in Fig. 2, for thecontrol valve 36 of the solenoid 39 and the cylinder 33. Thisarrangement provides a convenient means for assembling the apparatus fwith few pipe connections.

In order'that the rotation of the index wheel may be controlled by handin making the initial setting of the machine o r for any other purpose,there is provided a hand-operated cam 15 attached to the endof a rockershaft 16 (see Figs. 5 and 6) and underlying a projection 11 formed onthe rocker arm 24. The shaft 16 projects through the front wall of thecasing and is provided with an operating handle 18. When the shaft 16 isturned by means of the handle 13 the cam 15 will raise the arm 24 torelease the tooth 23 from engagement with the notches 22 in the indexwheel.

To avoid inadvertent release of the index wheel while the machine is inoperation there is preferably provided a lock for the shaft 16 whichpermits it to be turnedbnly when the electric control system isdisconnected. This mechanism comprises a rod 1.9 (see Fig. 3) supportedin suitable guides on the adjacent wall of the casing for limiting thelongitudinal movement. The end of the rod 19 engages a rocker arm 8i)pivoted on the wall of the casing and at its opposite end releasing thelever 90 so that the locking arm 90 is free to drop out of engagementwith the detent 83. As will be later described, the circuit of the coil82 is controlled bya switch whose operation also serves to break thecircuit of the electric control system.

Other safety devices may be provided if desired, forexample, a safetyswitch 85 such as shown in Fig. 7 may be employed to cut off the drivingmotor of the pumps 4 and 5 in case the reversing mechanism for the tablefalls to operate in properly timed sequence. This switch is operated bya plunger 86 projecting through the front wall of the casing of theindexing head in position to be engaged by a lug on the supportingcolumn of the grinding wheel and operate the rod 86 before the grindingwheel contacts the casing.

This safety device is particularly desirable for machines in which thegrinding wheel and the indexing head are both adjustable on theirrespective bases. The movement of the reciprocating table is determinedby the adjustment of the trips which operate the reversing switches ateach end of the tables movement. If the trips are not properly adjustedan accident and consequent damage to the machine will be averted by thelimit switch which will stop the reciprocation of the table before thegrinding wheel contacts the index head.

In addition to the safety switch carried by the indexing head Ipreferably provide a second safety switch for breaking the mainelectrical cirsuit should the belt which drives the grinding wheelbreak. This safety switch is shown in Fig. 10 and as there showncomprises an idle pulley |20 pivoted at |2| within the standard whichsupports the grinding wheel in position to bear against the belt |22through which the spindle of the grinding wheel is driven from itsmotor. The supporting arm |24 of the pulley |20 is pressed against thebelt by a suitable spring |23, the beit thereby maintaining thesupporting arm in substantially vertical position from which it will beshifted by the action of the spring should the beit break. The lower endof the supporting arm |24 is connected to a control switch |25 which Ihave illustrated diagrammatically as comprising a contact piece arrangedto close the gap between two conductors when the arm is in substantiallyvertical position and to open the gap between the conductors when thearm swings toward the horizontal. It will be understood that theillustration is diagrammatic and that in practice a circuit breaker ofusual construction will be employed.

In Fig. 11 I have illustrated the mechanical parts of the mechanism forcontrolling the reciprocation of the table. The table 1 is providedalong its front edge with a rack 90 and a parallel trackway 9| on whichis supported the adjustable blocks or stops 92 carrying dependingiingers 93 positioned to engage at their lower ends the exposed ends of4the trip rod 94 which, as described, is mounted for limitedreciprocating motion in a bearing 95 supported on the stationary frameof the base. Supported on a fixed pivot 99 in a covered box beneath thebearing 95 is an upstanding lever 91 whose upper end is forked to engagea pin on the rod 94 so as to be turned on its pivot by movement of therod in either direction. Lever 91 is maintained in vertical position bysprings 99 and will be shifted in one direction or the other by thedepending fingers 93 when these contact the end of the rod 94 as thetable reaches the end of its movement 8 as determined by the position ofthe blocks Il. Mounted in the box alongside the lever I1 is a combinedspeed regulating and deceleration valve 99 which serves to slow down themovement of the table when the lever 91 is shifted in either direction.The valve 99 is not shown in detail in this application but ispreferably of the construction shown in my co-pending application Ser.No. 489,943, filed June5, 1943, which has become abandoned. For thepurpose of this case it will be understood that this valve is arrangedin the discharge line from the hydraulic operating cylinder for thetable and may be adjusted to regulate the normal rate of flow from thecylinder. In addition, upon movement of the control knob |00 toward theright as shown in Fig. 11, it serves to further throttle the rate ofdischarge of the operating fluid from the cylinder, to thereby reducethe speed of movement of the table. The knob |00 is operated by crosslevers |0| arranged so that one lever will be shifted when the lever 91is turned in one direction from its neutral vertical position, while theother lever |0| will be shifted when the lever 91 is turned in theopposite direction. By this arrangement knob |00 will be shifted to theright upon movef ment of the lever 91 in either direction from itscentral neutral position.

The lever 91 also operates a control switch |92 'by means of which theindexing mechanism is set in operation at the end of the table movement.This switch is a two-position switch and as shown comprises a pivotedcontact member |09 which in one position establishes connection betweena pair of contacts at one side of its intermediate position and whenswung to its opposite position closes another pair of contacts. 'I'heswitch member |03 is heid in one closed position or the other by aspring |04. The switch is thus in one closed position or the other anddoes not return to central position as does the lever 91 when the tablestarts its movement in the opposite direction. The switch member |09 isoperated by a. sliding bar |04' connected to the lower end of the lever91 and provided with lugs |09 for engaging the member |03 when the leveris fully turned in one direction or the other.

Also shown in Fig. l1 is the control panel |09 in which are supportedthe switches for securing the desired predetermined cycle of operations.The construction and operation of these switches will be later describedin connection with the control circuit illustrated in Fig. 13.

In Fig. 12 I have illustrated the hydraulic circuit for effecting theoperation of the table and indexing head. As already described, twoseparate hydraulic circuits are employed. These pumps are drivencontinuously whenever the machine is in operation and through thepressure-regulating valves maintain constant operating pressure in theirrespective lines, which pressure may be accurately regulated and will bemaintained regardless of the amount of oli flowing through the pressureline within wide limits. The pressure-regulating valve is not shown indetail, but is preferably of the type disclosed in my co-pendingapplication Ser. No. 414,367, filed October 9, 1941, which has becomeabandoned. From the pressure-regulating valve for operating the table,'the pressure line extends to a four-way solenoid valve ||0 'whichcontrols the admission and discharge of oil from the opposite ends ofthe operating cylinder of the table in accordance with the predeterminedcycle of operations for which the machine is set. This valve is notshown in detail, but is preferably of the construction shown anddescribed in my co-pend- Ihg application Ser, No. 421,377, led December2, 1941, and which issued as Patent No. 2,363,111 on November 21, 1944.Its essential elements are a valve casing containing a valve body IIIwhich is normally maintained in central position by suitable springs, asshown. The valve body has two spaced heads which normally close the-ports connected to the ends of the cylinders. When shifted to the rightthe valve connects the pressure line I I4 to the right end of thehydraulic cylinder, and when shifted to the left connects the left endof the cylinder to the pressure line, and the other end of the cylinderto the discharge line H3. The line H3 leads to the deceleration valve 99and thence to the sump, from which oil is returned to the circuit.

The movement of the Valve body is controlled by solenoids H5, H6,supported on the valve casing and arranged to operate pilot valves, notshown, but which upon energizing of the solenold admits pressure fromthe pressure line to the adjacent end of the valve casing to eect themovement of the valve body IH. That is to say. when the solenoid H5 isenergized pressure is admitted to the left end of the valve casing,thereby shifting the valve body to the right and admitting pressure tothe right end of the hydraulic cylinder. The solenoids H5, H6 areenergized after the index head comes to rest, whereby the movement ofthe table will occur only when the index head is stationary and likewisethe control of the index head latch is effected through the movement ofthe table in such manner that the index head is held against movementuntil after the table comes to rest.

The hydraulic control for the indexing head has already been described.The sequence of operations with the control set for indexing at each endof the table movement is as follows: Assuming the table to be movingtoward the left as shown in Fig. 12, the right stop nger 93 will engagethe movable bar 94 and turn the lever 91 on its pivot. The rst movementof the lever serves to shift the knob of the speed regulating andde-celeration valve 99, thereby checking the speed of the table so thatit comes to a. stop without jar when the lever reaches the end of itsmovement.

Just before the lever reaches the end of its movement the switch member|03 will be snapped to open the contacts for the valve H6 and close thecontacts for the valves H5, through the electric control system whichwill now be described. The shifting of the lever |03 does notimmediately energize the coil of the solenoid H5, but instead thecircuit is closed through the relay which controls the movement of thelatch 23, lifting the latch and releasing the index wheel so thatindexing takes place. As the index Wheel nears the completion of itsmovement the arm 50 is rocked, releasing the control valve for the latch23, which valve, on returning to its normal position, cuts OIT in partthe discharge line from the fluid motor driving the index head, therebychecking the speed of the index head and permitting the parts to bebrought to rest without jar or vibration. When the indexing operation iscompleted as described the circuit is closed through the solenoid valveH6, which opens its Y attached pilot valve, delivering fluid underpressure to the right hand end of the valve H0. thereby admitting iluidunder pressure to the left end of the hydraulic cylinder which willcause the table to start on its return movement.

The control apparatus for effecting the sequence of operations is shownin Fig. 13. The electric control system here disclosed comprisesconnections whereby the machine may be automatically operatedcontinuously through several different cycles. The machine may be set toindex the work at each end of the table movement or it may be set toindex the work at one end only of the table movement, either right orleft. Connections are also provided whereby the indexing operation maybe discontinued without aiecting the automatic reciprocation of thetable. Also, a control is provided whereby the reciprocati'on of thetable may be discontinued and the index head turned continuously.Connections are also provided whereby the indexing may be controlled byhand and also the movement of the table to the right or left may becontrolled through hand-operated switches without disconnecting orresetting the automatic cycle control.

In Fig. 13 various control elements are shown in position for continuousautomatic operation with indexing at each end`of the table movement. Theparts are shown in the positions they occupy when the table has justcompleted its movement to the right and the indexing has taken place,but before the movement to the left begins. The circuits will bedescribed in the sequence that they would become operative if themachine were started from this position by closing the cycle switch.

The positive and negative sides of the-electricy control circuit arehere represented by conductors 230, 232, respectively. Conductor 232 isconnected through the control circuit to the master switch 20| whichmust be closed by hand before any part of the machine may be set inoperation. From the master switch the circuit leads through safetyswitches 05 and |25 to a second hand switch 202 which controls theoperation of y the grinding spindle and coolant motors. Thence thecircuit leads to a switch 203 which controls the pump motor. A lead 204from switch 203 constitutes one side of the control circuit. One branchof the circuit 204 leads to switch A of the main cycle relay CRI. Thisrelay has two switches CRIA and CRIB. bothof which are normally open butare closed when cycle switch C5 is closed by hand to energize the relaycoil through conductor 209 which leads through certain control switcheswhich will be later described, to the coil of the relay.

Energizing the coil of relay CRI closes both switches CRIA and CRIB.From 'switch CRIA conductor 205 leads to switch "which, as previouslydescribed, is actuated by the latch 23 which holds the index wheelagainst movement. The switch l1 is closed when the latch 23 is in lockedposition and connects conductor 205 to a lead 2 I0 from which twobranches 234, 235, lead to contacts on opposite sides of thetwo-position switch |02 which controls the table movement. With thetable in the position shown the lead 234 is connected by the switch |02to a conductor 231 which leads to one contact of the switch RIC ol thetable control relay RI through which the movement of the table towardthe right is effected. This switch RIC is normally closed and throughthis switch current passes to a conductor 206 which leads to the coil ofthe relay LI which controls the movement of the table to the left. Thecoil of LI will therefore be energized when the cycle switch is closedand the relay CRI energized and will lift a,44a,ess

the relay, closing switches LIA and LIB, and opening switch LIC. At thesame time through another branch of 206 the solenoid at the left end ofthe table control valve IIO is energized, thereby shifting the tablecontrol valve in a direction to admit fluid under pressure to the righthand end of the table-operating cylinder, thus causing the table to moveto the left.

Closing switch CRIB connects the coil of a second cycle relay CR2 to thepositive side 230 of the circuit. The other end o! the coil is connectedto one terminal of the switch 52 which is actuated by the trigger" l andis closed except when the trigger drops into the notches of the indexwheel while the wheel is turning. From the other side of the triggerswitch the circuit leads to switch CR2B, which is closed when the coilof CR2 is deenergized, thence through conductor 2 I 2 to switch LIAwhich is closed during the movement of the a table from right to left.From the other contact of switch LIA a conductor 2I0 leads to thecyclesetting switch CS, all four elements of which are closed whenindexing is to take place at both ends of the able movement.y Throughthis switch the circuit leads through 2I6 and 236 to the right hand sideof table switch |02 which is open during the movement of the table fromright to left. When the table completes its movement from right to lettthe switch |02 will be shifted to the right, opening the contacts on theleft and closing those on the right, thus connecting 230 to 2I0, thencethrough the latch switch 41, through 205 to the negative side oi' thecircuit, thus energizing the coil of relay CR2, opening switch CR2B andclosing CR2A and CR2C.

Closing CRZC energizes the coil o! the latchcontrol valve 36 throughconductor 23| to coil 39 and conductor 245, thereby causing the latch tolift through the action of the piston 35 and rocker 30, releasing theindex wheel and opening the latch switch 41. Opening the latch switchdeenergizes the coils of the left solenoid of the table control valveand of relay LI, allowing LIC to close and opening LIB and LIA. As theindex wheel in under constant torque from its driving motor the indexingwheel will begin to turn and will continue at its maximum speed untilthe next notch reaches the trigger and the trigger drops into the notch,thus opening the trigger switch and de-energizing the coil of CR2. CB2drops, opening CR2A which de-energizes the coil of the latch controlvalve which will be shifted by its spring to cut on the pressure fromthe latch opening piston 35 and also throttle the return conduit fromthe operating motor of the index head, reducing the speed of the motorso that the index wheel will come to rest without Jar or vibration whenthe latch drops into the advancing notch.

When the latch is fully seated in the notch the latch switch will closeand as the table control switch |02 is now in its right hand positionthe coils of relay RI and the solenoid at the right end of thetable-control valve will be energized and the table will move to theright. Upon completion of its movement the indexing operations abovedescribed will be repeated.

If desired the index wheel may be operated at one end only of the tabletravel. For this purpose I provide the cycle control switch CS. Thisswitch is designed so that in mid-position all four elements will beclosed and when adjusted to left the upper left and lower right will beopened, while the other two elements will be opened when the switch isadjusted in the other 12 direction. Let us assume that the table ismoving to the left and the switch CS is set so that no indexing willtake place at the completion of the movement in that direction, that is,the switch handle is set in the right hand or dot-anddash position, asshown in Fig. 13.

With the switch CS set in position with all four elements closed thecircuit extended, during the travel of the table toward the left, fromconductor 2I2 to switch LIA to conductor 2I8, thence through the lowerleft hand element of switch CS to conductor 236 to the right contact oftable switch |02, so that when switch |02 is shifted at the end of thetable movement the circuit is closed through the coil of relay CR2, thusenergizing the solenoid of the latch control valve and releasing theindex wheel and opening the latch switch. With the switch CS adjusted tothe right, the circuit from 2I8 to 236 ls broken and consequently thecoil of relay CR2 is not energized and the index head is not released.Instead the opening of the contacts 231, 235 at the left of table switch|02 at the completion of its movement to the left immediatelyde-energizes the coils of LI and the left solenoid of the table controlvalve i-or the hold-in circuit for these coils through 2I1, 2H and LIBis broken at the upper right hand element of the switch CS which is openwhen the handle of switch CS is adjusted to its right hand position.

De-energizing these coils returns the table control valve to its middleposition and closes LIC, so immediately switch |02 is shifted to theright as the table completes its movement to the left, the coils of theright solenoid of the table control valve and relay RI will beenergized, starting the table on its return movement and closing RIA andRIB. Conductors 2I9 and 2I5, respectively, lead from these switches tothe lower right and upper left elements of the switch CS and as theseswitches are closed when the handle of switch CS is adjusted to theright the indexing, when the table reachesythe end of its travel towardthe right will take place in' the manner described.

It it be desired to index only when the table is at the end of itstravel toward the left, the switch CS is adjusted to its left handposition, thus closing the circuits controlled by switches LIA and LIBand opening the circuits through RIA and RIB.

In order for the table to be continuously reciprocated without indexingat either end of its travel, a separate switch S2 is provided which,when adjusted to its off position breaks the circuits through LIA andLIB and also through RIA and RIB, so that the latch-control valveremains closed and the table-control valve is controlled directly by thetable switch I 02.

It is sometimes desired to rotate the index wheel continuously withoutmoving the table. For this purpose I provide a switch S3 which, in itsnormal position of adjustment for cycle operation, closes the circuitthrough the coil of cycle relay CRI. When adjusted to its continousindex position, the circuit through the coil of CRI is broken and acircuit established through one branch of the switch directly fromnegative lead 204 through a conductor 245 to the coil of thelatch-control valve, thence through conductor 23| and the other branchof switch S3 to positive lead 230. The latch is thus held in releasedposition and the circuit through the table-control valve |02 ismaintained open. The leads from the switch S3 are omitted for clar- 13ity in the Fig. 13. but it will be understood that the terminals areconnected to the indicated conductors.

It may also be desired to control the indexing by hand. which of coursemay be done only when the table is stationary at one end of itsmovement. In order to control the movement of the index wheel by hand,it is necessary to lift the latch, and this is accomplished by the lever18 which, as previously described, is locked against motion by the latch80' and solenoid 82. The coil of this solenoid, as shown in' Fig. 13, iscontrolled by a two-element hand switch S4 one element of which closesthe circuit through the coil ofthe solenoid l2 while the other elementis in the circuit of the coil of the cycle relay CRI. By thisarrangement the index wheel cannot be released by hand without openingthe circuit through the solenoid 82 by means of the switch S4, whichswitch also opens the circuit through the cycle relay, whereby the tablecomes to rest at the end of its movement and remains at rest until thecircuit is re-established by closing the switch S4.

Means are also provided for controlling the reciprocation of the tableby hand. To this end switches S5 and S6 are provided one for eachdirection of movement of the table. These switches, as shown in Fig. 13,are two-position switches and in one positionthe position of each switchfor normal cycle operation-they close the circuit through the coil ofthe cycle relay CRI so that shifting either switch from cycle operationposition releases the relay CRI. In the other position of operation theswitch S5 completes the circuit directly through the coils on the leftof the solenoid of the table control valve and the relay Ll, therebyeiecting an immediate movement of the table to the right. In likemanner, when the switch S6 is in its noncycle position, the circuit iscompleted directly through the coils of the right hand solenoid of thetable control valve and the relay RI and the table will thereby beimmediately moved toward the left where it will come to rest and remainat rest until the switch is restored to cycle position.

The above described electric control system gives complete and universalcontrol to the movement of the table, but it will be understood ofcourse that it is not necessary to provide for all the automatic cyclesobtainable with this circuit, nor are the various safety devidesessential to the. operation of the machine. and it will be un. derstoodthat the electric control circuit may be variously modified within thescope of the invention.

In Figs. 14 and 15 I have illustrated a modied i'ormA of indexhead-designed primarily for use when the machine is to be employedforgrinding gear teethor splines by the alternate face method. In carryingout the grinding according to usual methods a grinding wheel is employedwhich is accurately dressed to the shape and dimensions of the spacingbetween the two adjacent splines or teeth. The work is indexed to bringthe successive spaces between the splines or teeth accurately beneaththe grinding wheel and the latter is then lowered into grinding positionso as to simultaneously dress the face of two adjacent teeth or keys. Itis sometimes desirable to dress one face only at a time. For thispurpose a grinding wheel is used which is thinner than the space betweenthe adjacent teeth so that it may be lowered between the adjacent teethto the bottom ot the space between the 14 teeth without contacting theside faces of the adjacent teeth, and then pressed laterally in onedirection against one surface to be ground and then laterally in theopposite direction against the other surface to be ground.

In order to carry out this sequence of operations it is necessary notonly to turn the work accurately through the required angle, dependingupon the number of teeth in the gear, but

also to thereafter turn a slight distance iirst in one direction andthen in the other to bring the face to be ground into contact with theside face of the grinding wheel.

In the machine forming the subject-matter of the present application Iaccomplish this sequence of operations by indexing in the usual mannerto eiect the movement of the work through the predetermined angle tobring the successive portions to be ground'into alignment with thegrinding wheel and then effect the supplemental movement of the work byshifting the entire support for the index head by a hydraulic c'ontrolmechanism such as illustrated in Figs. 14 and 15.

Referring to Fig. 14, it will be seen that the arm 25 which supports themembers 24 and 50 and is locked in adjusted position by means of theclamp 28, is provided with an extension |26 projecting through aslot inthe top of the housing a of the indexingl head and is provided with alug |21 positioned to be engaged by two opposite stop members |28, |29,which are mounted for movement toward and away from each other in asupplemental housing |30 mounted upon the upper face of the indexhousing 8. The stop members |28 and |29 are internally threaded withrightand left-hand threads, respectively, for receiving an adjustingscrew |3| which is similarly threaded and mounted for rotation in anextension of the bore in which the stops |28, |29 are supported. The endof the screw |3| is provided with an extension |3|a connected to themain portion of the screw by a tongue-andslot connection, as shown inFig. 14, which D81'- mits relative longitudinal movement of the screwand extension but connects them for rotative movement. The extension|3|a projects beyond the end wall of the housing |30 and is providedwith an adjusting knob |32 having a graduated dial for facilitatingaccurate adjustment of the screw and with a lock nut |33 for locking thescrew in adjusted position.

Rotation of the adjusting screw in one direction draws the stop memberstoward each other to thereby clamp the lug |21 rmly against movement ineither direction, while movement. in the opposite direction-moves thestops equally and oppositely apart to thereby permitl a movement of thesupporting arm 35 to a limited extent in both directions from theposition in which it was locked when the steps were clamped against thelug.

In order to accurately adjust the position oi the supporting arm 25 thescrew |3|, including the stops |29 and |29, can be shifted laterally to/accurately position the arm 25 in its normal locked position. Tofacilitate the accurate moveprovide a hydraulic cylinder |39 whosepiston |40 engages a pin |4| bearing against the side of the lug |21.The cylinder is connected through a hand valve |42 to the pressure lineleading to the operating motor I for the index wheel. As explainedabove, the index wheel is normally maintained under the driving torqueof the motor and constantly tends to turn in a counterclockwisedirection as viewed in Fig. 14. As the index wheel is normally locked tothe support by the member 24, the torque of the motor tends to turn thesupport likewise to a counterclockwise direction so that when the screw|32 is turned to separate the stops and the clamping nut 26 is releasedthe support 25 and the entire index wheel and connected mechanism willturn in a counterclockwise direction through the distance permitted bythe separation of the stops. The piston |40 is, however, of 'suilicientarea to overcome the torque of the hydraulic motor I8 when the piston|40 is subjected to the pressure from the pressure line and thereby whenthe valve |42 is opened the support 25 will be shifted in a clockwisedirection to the full extent permitted by the separation of the stops.In operation the support 25 is accurately adjusted by means of the screw|31 for the normal indexing operation and is clamped in that position bythe clamp 25. After the indexing movement which serves to bring thecenter of the space between the teeth to be ground in proper alignmentwith the central plane of the grinding wheel, the screw |32 will beturned through the proper arc to separate the stops the desired amountand the clamping nut 26 is released. The torque of the driving motorturns the arm 26 in a counterclockwise direction to bring the lug |21against the stop |30 which is accurately positioned to bring the surfaceto be ground in proper position for engagement with the side face of thegrinding wheel. After this surface has been suidciently dressed thevalve |42 is opened, admitting pressure to the cylinder |39 and therebyshifting the support 25 in a clockwise direction until the lug |21engages the stop |29, thereby positioning the surface of the oppositetooth in position to be dressed by the opposite side face of thegrinding wheel.

The above described mechanism does not in any way interfere with theordinary grinding operations wherein the work is held against rotationat each index position throughout the grinding operation.

It will of course be understood that while the above described mechanismrepresents a typical embodiment of my invention which has been foundhighly satisfactory in precision grinding, the invention is not limitedto the construction shown and described except insofar as recited in theappended claims.

I claim:

1. In a machine tool of the class described comprising an indexing headand a. reciprocating table, means for periodically rotating saidindexing head, means for reciprocating said table, and an electriccontrol system for automatically effect- 16 ing the operation of saidparts in predetermined sequence, comprising means for adjusting saidsystem to cause the operation of said index head at each end of eachmovement of said table or at one end only of said movement.

2. In a. machine tool of the class described, a. reciprocating table,means for operating the same comprising a hydraulic cylinder, means forsupplying operating fluid under pressure to said cylinder, controlmechanism for controlling the supply of fluid comprising a valve in thedischarge line from said cylinder and means for adjusting said valve topartially close said discharge line as the table nears the end of itsmovement, a second valve for reversing the supply and dischargeconnections of said cylinder, means for eii'ecting the operation of saidsecond valve at a predetermined time after said table is stationary.said means comprising an electric control circuit for said valve, aswitch operated by said table for setting said circuit, a second switchfor closing said circuit and means independent of the table movement forcontrolling said second switch.

3. In a machine tool an indexing head comprising a work-rotating shaft,a motor for operating the same, a notched indexing wheel attached tosaid shaft, a locking pawl for engaging said notches, means forcontrolling the motor of the shaft to automatically reduce the speed ofthe motor immediately prior to the locking of the index wheel, and asupport for said pawl and said last named means mounted for adjustmentaround the axis of rotation of said shaft.

4. In an indexing head for machine tools cornprising a work-supportingshaft, an index wheel attached thereto provided in its periphery withspaced notches for locking the work-supporting shaft in differentpositions, a locking member adapted to successively engage the notchesin said wheel to thereby lock the wheel against movement, a hydraulicmotor for turning the index wheel and means for reducing the speed ofsaid motor, said means comprising a trip member mounted adjacent theindexing wheel in position to be engaged and tripped by the notches inthe wheel as the latter approach their locked position.

5. In an indexing head for machine tools comprising a work-supportingshaft, an index wheel attached thereto provided in its periphery withspaced notches for locking the work-supporting shaft in differentpositions, a locking member adapted to successively engage the notchesin said wheel to thereby lock the wheel against movement, a hydraulicmotor for turning the index wheel and means for reducing the speed ofsaid motor, said means-comprising a trip member mounted adjacent theindexing wheel in position to be engaged and tripped by the notches inthe wheel as the latter approach their locked position, said lockingmember and said trip member being mounted for adjustment around the axisof rotation of said shaft.

6. In an indexing head for machine tools comprising a work-supportingshaft, an index wheel attached thereto provided in its periphery withspaced notches for locking the work-supporting shaft in differentpositions, a locking member adapted to successively engage the notchesin said wheel to thereby lock the wheel against movement, a hydraulicmotor for turning the index wheel, a. valve for controlling the speed ofsaid motor, and means for adjusting the valve to reduce the speed ofsaid motor, said means comprising a trip member mounted adjacent theindexing wheel in position to be engaged and tripped by the notches inthe wheel as the latter approach their locked position.

7. In a machine tool an indexing head comprising a work-rotating shaft,means for periodically locking said shaft against rotation, a hydraulicmotor having a continuously rotating shaft for rotating said shaft andmaintaining a constant driving torque on said shaft While it is held inlocked position, a reciprocating support for said indexing head, meanscontrolled by the movement of said support for releasing sai-d lockingmeans to permit rotation of said shaft while said support is stationaryand means for preventing reciprocation of said support while said shaftis rotated.

8. In a machine tool an indexing head comprising a work-rotating shaft,means for periodical- 1y locking said shaft against rotation, ahydraulic motor having a continuously rotating shaft for rotating saidshaft and maintaining a constant driving torque on said shaft while itis held in locked position, a reciprocating support for said indexinghead, means controlled by the movement of said support for releasingsaid locking means to permit rotation of said shaft while said supportis stationary and means for preventing reciprocation of said supportwhile said shaft is rotated, said means comprising a switch forcontrolling the drive of said support and connections between saidswitch and said locking means for shifting said switch upon the movementof said means to locking position.

9. In a machine tool of the class described, an index head comprising anindex wheel, means for rotating the same, means for locking said wheelin predetermined positions, a support for said locking means mounted formovement concentric with the axis of rotation of said index wheel, meansfor adjusting said support to a pre- 18 determined position and meansindependent of said adjusting means for shifting said support inopposite directions from said position of adjustment and restoring saidsupport accurately to said `adjusted position.

10. In a machine tool of the class described, an index head comprisingan index wheel, means for rotating the same, means for locking saidwheel in predetermined position, ya support for said locking meansmounted for movement concentric with the axis of rotation of said indexwheel, means for adjusting said support to a predetermined position andmeans independent of said adjusting means for shifting said support inopposite directions from said position of adjustment and restoring saidsupport -accurately to said adjusted position, said means comprising asource of hydraulic pressure and connections for applying unbalancedhydraulic pressure optionally in opposite directions against said sup-Dort.

RACY D. BENNETT.

REFERENCES CITED The following references are of record in the le ofthis patent:

UNITED STATES PATENTS Number Name Date 1,583,351 Heald May 4, 19261,745,460 Sudhoi Feb. 4, 1930 1,850,799 Junge Mar. 22, 1932 1,973,329Bullows Sept. 11, 1934 2,012,273 Fraser Aug. 27, 1935 2,118,139 Bath etal. May 24, 1938 2,206,492 Westenberger et a1. July 2, 1940 2,257,850Miller Oct. 7, 1941 2,258,510 Laesaker Oct. 7, 1941 2,292,588Terbrueggen Aug. 11, 1942 2,296,731 Mustonen Sept. 22, 1942 2,349,602Baldenhofer May 23, 1944

